Boundary designs

The optimization method minimize is based on the package nloptr. This requires upper and lower boundaries for optimization. Such boundaries can be computed via lower_boundary_design respectively upper_boundary_design. They are implemented by default in minimize. Note that minimize allows the user to define its own boundary designs, too.

get_lower_boundary_design(initial_design, ...)

get_upper_boundary_design(initial_design, ...)

# S4 method for OneStageDesign
get_lower_boundary_design(initial_design, n1 = 1, c1_buffer = 2, ...)

# S4 method for GroupSequentialDesign
get_lower_boundary_design(
  initial_design,
  n1 = 1,
  n2_pivots = 1,
  c1_buffer = 2,
  c2_buffer = 2,
  ...
)

# S4 method for TwoStageDesign
get_lower_boundary_design(
  initial_design,
  n1 = 1,
  n2_pivots = 1,
  c1_buffer = 2,
  c2_buffer = 2,
  ...
)

# S4 method for OneStageDesign
get_upper_boundary_design(
  initial_design,
  n1 = 5 * initial_design@n1,
  c1_buffer = 2,
  ...
)

# S4 method for GroupSequentialDesign
get_upper_boundary_design(
  initial_design,
  n1 = 5 * initial_design@n1,
  n2_pivots = 5 * initial_design@n2_pivots,
  c1_buffer = 2,
  c2_buffer = 2,
  ...
)

# S4 method for TwoStageDesign
get_upper_boundary_design(
  initial_design,
  n1 = 5 * initial_design@n1,
  n2_pivots = 5 * initial_design@n2_pivots,
  c1_buffer = 2,
  c2_buffer = 2,
  ...
)

Arguments

initial_design

The initial design

...

optional arguments

The values c1f and c1e from the initial design are shifted to c1f - c1_buffer and c1e - c1_buffer in get_lower_boundary_design, respectively, to
c1f + c1_buffer and c1e + c1_buffer in get_upper_boundary_design. This is handled analogously with c2_pivots and c2_buffer.

n1

bound for the first-stage sample size n1

c1_buffer

shift of the early-stopping boundaries from the initial ones

n2_pivots

bound for the second-stage sample size n2

c2_buffer

shift of the final decision boundary from the initial one

Examples

initial_design <- TwoStageDesign(
  n1    = 25,
  c1f   = 0,
  c1e   = 2.5,
  n2    = 50,
  c2    = 1.96,
  order = 7L
  )
get_lower_boundary_design(initial_design)
#> TwoStageDesign<n1=1;-2.0<=x1<=0.5:n2=1>